Volume amplitude limiting device

Title: Volume amplitude limiting device.Abstract: A volume amplitude limiting device includes a volume adjustment unit, an amplitude limiting unit, and a control unit. The volume adjustment unit adjusts the amplitude of an input sound signal to a larger degree as the adjustment value increases and outputs the resulting sound signal. The amplitude limiting unit limits the amplitude of the sound signal output from the volume adjustment unit to an output limitation value and outputs the resulting signal to a speaker. The control unit sets an adjustment value for the volume adjustment unit and also sets an output limitation value for the amplitude limiting unit according to an adjustment value. ...

TECHNICAL FIELD

The present invention relates to a volume amplitude limiting device, more specifically to a volume amplitude limiting device that, for low-volume sound output from a speaker, prevents the sound from becoming unpleasant due to enclosure noise and speaker distortion through amplitude limitation; and for high-volume sound, supplies the sound signal to the speaker up to the rated output.

BACKGROUND

Conventionally, to reduce distortion of sound output from a speaker or to suppress overmodulation of broadcast output, a sound signal limiting amplifier that limits sound output to a given value is widely used (refer to patent literature 1 for example).

A description is made of a configuration of sound signal limiting amplifier 300 described in patent literature 1 using FIG. 16. An input sound signal to input terminal 310 typically contains all the frequency components from low frequency range to high frequency range. The input sound signal passes through low frequency selector circuit 311a as a low-pass filter that limits the frequency bandwidth to a predetermined frequency. On the other hand, the sound signal similarly passes through high frequency selector circuit 311b as a high-pass filter. The sound signals having passed through low frequency level limiting amplifier circuit 312a and high frequency level limiting amplifier circuit 312b are synthesized by adder circuit 313 and are output to output level limiting amplifier circuit 314.

When a signal level of a signal having passed through low frequency selector circuit 311a does not undergo level limitation by low frequency level limiting amplifier circuit 312a and a signal level of a signal having passed through high frequency selector circuit 311b does not undergo level limitation by high frequency level limiting amplifier circuit 312b, a signal synthesized from the two signals by adder circuit 313 is output with its frequency characteristics remaining flat.

Meanwhile, when a sound signal with its amplitude of low-frequency components larger than that of high-frequency components is input to input terminal 310, the sound signal having passed through low frequency selector circuit 311a undergoes level limitation by low frequency level limiting amplifier circuit 312a. On the other hand, a sound signal having passed through high frequency selector circuit 311b does not undergo level limitation by high frequency level limiting amplifier circuit 312b. Hence, conducting the signals through adder circuit 313 provides output signal h with only its low components level-limited and with its high components not level-limited. However, adding operation by adder circuit 313 can cause a given reference limitation level to be exceeded. In this case, output signal h is level-limited by output level limiting amplifier circuit 314 and is eventually output as output signal i.

In the meantime, a volume amplitude limiting device is typically designed to specifications such that the level of a sound signal to be input does not exceed the maximum rated value of a speaker or sound amplifier. However, equipment with an actual speaker built-in often produces unpleasant sound due to resonance of the housing of the equipment or sound distortion of the speaker even if output from the speaker does not exceed the maximum rated value. Accordingly, to keep pleasant sound quality, sound output needs to be limited within a range lower than the maximum rated value of the speaker or sound amplifier so as to avoid resonance of the housing of the equipment and sound distortion of the speaker. However, with amplitude limitation of a sound signal at such a low value, the rated output value according to product specifications cannot be output.

CITATION LIST
Patent Literature

PTL 1 Japanese Patent Unexamined Publication No. H08-316760

SUMMARY

A volume amplitude limiting device of the present invention includes a volume adjustment unit, an amplitude limiting unit, and a control unit. The volume adjustment unit adjusts the amplitude of an input sound signal to a larger degree with increase in an adjustment value and outputs the resulting sound signal. The amplitude limiting unit limits the amplitude of the resulting sound signal output from the volume adjustment unit to an output limitation value and outputs the resulting sound signal to a speaker. The control unit sets an adjustment value for the volume adjustment unit and also sets an output limitation value for the amplitude limiting unit according to the adjustment value.

With such a configuration, the control unit of a volume amplitude limiting device of the present invention can set an output limitation value for the amplitude limiting unit according to the adjustment value. Hence, the device limits the amplitude of a low-volume of input sound signal to prevent output from a speaker from becoming unpleasant due to enclosure noise and speaker distortion while supplying high-volume sound to the speaker up to the rated output value.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing a configuration of a volume amplitude limiting device according to the first exemplary embodiment of the present invention.

FIG. 2 shows an example of a concept on which the control unit of the volume amplitude limiting device controls the amplitude limiting unit according to the first exemplary embodiment of the present invention.

FIG. 3 shows another example of a concept on which the control unit of the volume amplitude limiting device controls the amplitude limiting unit according to the first exemplary embodiment of the present invention.

FIG. 4 shows yet another example of a concept on which the control unit of the volume amplitude limiting device controls the amplitude limiting unit according to the first exemplary embodiment of the present invention.

FIG. 5 shows still another example of a concept on which the control unit of the volume amplitude limiting device controls the amplitude limiting unit according to the first exemplary embodiment of the present invention.

FIG. 6 shows further another example of a concept on which the control unit of the volume amplitude limiting device controls the amplitude limiting unit according to the first exemplary embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a volume amplitude limiting device according to the second exemplary embodiment of the present invention.

FIG. 8 shows an example of a concept on which the control unit of the volume amplitude limiting device controls the first amplitude limiting unit according to the second exemplary embodiment of the present invention.

FIG. 9 shows an example of a concept on which the control unit of the volume amplitude limiting device controls the second amplitude limiting unit according to the second exemplary embodiment of the present invention.

FIG. 10 shows another example of a concept on which the control unit of the volume amplitude limiting device controls the first amplitude limiting unit according to the second exemplary embodiment of the present invention.

FIG. 11 is a block diagram showing a configuration of another example of a volume amplitude limiting device according to the second embodiment according to the second exemplary embodiment of the present invention.

FIG. 12 shows an example of a concept on which the control unit of another example of volume amplitude limiting device controls the second amplitude limiting unit according to the second exemplary embodiment of the present invention.

FIG. 13 is a block diagram showing a configuration of a volume amplitude limiting device according to the third exemplary embodiment of the present invention.

FIG. 14 shows an example of a concept on which the control unit of the volume amplitude limiting device controls the first amplitude limiting unit according to the third exemplary embodiment of the present invention.

FIG. 15 shows an example of a concept of operation of the second amplitude limiting unit of the volume amplitude limiting device according to the third exemplary embodiment of the present invention.

FIG. 16 is a block diagram showing a configuration of a conventional sound signal limiting amplifier.

You can also Monitor Keywords and Search for tracking patents relating to this Volume amplitude limiting device patent application.

###

How KEYWORD MONITOR works... a FREEservice from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Volume amplitude limiting device or other areas of interest.###

Data source: patent applications published in the public domain by the United States Patent and Trademark Office (USPTO). Information published here is for research/educational purposes only. FreshPatents is not affiliated with the USPTO, assignee companies, inventors, law firms or other assignees. Patent applications, documents and images may contain trademarks of the respective companies/authors. FreshPatents is not responsible for the accuracy, validity or otherwise contents of these public document patent application filings. When possible a complete PDF is provided, however, in some cases the presented document/images is an abstract or sampling of the full patent application for display purposes. FreshPatents.com Terms/Support -g2-0.1856